The present invention relates to a new and improved construction of gas-blast switch actuatable by a mechanical drive by means of a drive element.
Generally speaking, the gas-blast switch of the invention comprises a switch housing and connected thereto a through-passage housing containing a liquid bath, through which the drive element is guided out of the switch housing. A gas-blast switch of this type is known, for instance, from Swiss Pat. No. 385,955 and German Pat. No. 1,081,542. The liquid bath facilitates the sealing of the internal space of the switch housing against the external space or surroundings and in which the switch drive is most commonly located. The internal space or chamber of the switch housing is filled under pressure with a electronegative gas, like for instance, SF.sub.6.
Mechanical switch drives, in particular drives with a spring force storage, are preferable to comparable hydraulic switch drives, as known, for instance, from Swiss Pat. No. 601,910, since they are simpler in design, and therefore, more reliable in operation as well as working with reduced inertia.
At the beginning of a switching stroke considerable masses have to be accelerated and, at the end of the stroke, have to be again braked.
Various measures have been proposed to achieve this braking of the moving elements or parts in gas-blast switches, including switches where the drive element is not guided through a liquid bath. Commonly these measures consisted in operatively associating with the drive unit a separate hydraulic or pneumatic braking or damping device which came into operation at the end of a switching stroke, i.e. a cut-on or a cut-off stroke. Designs of this type require a certain additional constructional expenditure at the drive unit which thus becomes more complicated and less reliable in operation.